1. Field of the Invention
The present invention relates to a multi-processor system and a memory accessing method.
2. Description of the Related Art
In recent years, a multi-processor system including a plurality of processors has been developed in order to improve processing performance.
FIG. 1 shows a schematic diagram of a multi-processor system of a first conventional example. The conventional multi-processor system includes an operating system (OS), a plurality of MPUs (Micro Processing Units) operating on the operating system (OS), and a main memory. The plurality of MPUs share the main memory. The multi-processor system further has input/output (I/O) units (not shown). The plurality of MPUs share the I/O units. In such a conventional multi-processor system, when a trouble such as abnormality or fault has occurred in a part of the resource such as the main memory and the I/O units shared by the plurality of MPUs, there is a possibility that the trouble influences on the entire system.
From the viewpoint of the plurality of operating systems running on a single computer system, a virtual machine (VM) system is known as a second conventional example. FIG. 2 shows a schematic diagram of the virtual machine (VM) system. The virtual machine system includes a host operating system (OS) running on the computer, and a plurality of guest operating systems running on the virtual machine. In the virtual machine system, the host operating system (OS) is first started on the computer to operate the virtual machine. The plurality of guest operating systems run on the virtual machine generated on the host operating system (OS). However, in the virtual machine system, when a trouble such as abnormality or fault has occurred in a hardware resource in association with the host operating system (OS), or when the trouble has occurred in the host operating system (OS), the plurality of guest operating systems running on the virtual machine receive the influence of the trouble. Thus, the trouble has influence on the entire system.
Moreover, a logic dividing system is known as a third conventional example. FIG. 3 shows a schematic diagram of the logic dividing method. The logic dividing system includes an MPU and a plurality of operating systems running on the MPU. In the logic dividing system, a host operating system (OS) is not needed unlike the virtual machine system, but the plurality of operating systems run on the same computer. However, in the logic dividing system, since the plurality of operating systems run on the single MPU, the plurality of operating systems receive the influence of a trouble, when the trouble has occurred in the MPU. Hence, the trouble has influence on the entire system.
In conjunction with the above description, Japanese Laid Open Patent Application (JP-A-Heisei 5-204760) discloses a control system of a virtual machine system. The virtual computer system of this conventional example is provided with a plurality of operating systems and a management program for managing the plurality of operating systems. Under the control of this management program, the plurality of operating systems run on a single computer system. A control system of a virtual computer system includes a virtual address—real address converting section and a real address—absolute address converting section. The virtual address—real address converting section assigns a plurality of continuous spaces on a main memory to the plurality of operating systems, and has an address management table. The virtual address—real address converting section uses an address conversion table in the operating system to convert a virtual address into a real address. The real address—absolute address converting section converts the real address obtained by this virtual address—real address converting section to a physical address of the main memory by using the address management table.
Also, Japanese Laid Open Patent Application (JP-A-Heisei 2-96833) discloses a job control system. An information processing apparatus for the job control system of this conventional example includes a central processing unit, a main memory, an input/output processor and peripheral units connected to the input/output processor. The control of information processing to be carried out by the information processing apparatus is based on a general-purpose control section stored in a memory region of the main memory. In the job control system, the general-purpose control section has a section for starting a job of a model control section operating under a control of the general-purpose control section, and a section for reserving continuous memory regions different from a memory management region for the general-purpose control section in the main memory when starting the job. The reserved memory region stores sub jobs to be executed under the control of the model control section, a job memory management section of the model control section, a job task management section of the model control section, and a job interruption control section of the different model control section.
Also, Japanese Laid Open Patent Application (JP-P2001-101032A) discloses an operating system (OS) monitoring system for control between different operating systems. The operating system monitoring system of this conventional example detects an occurrence of a software trouble in a computer system on which a plurality of operating systems run. The operating system (OS) monitoring system has a function of separating hardware resources for the plurality of operating systems by using a virtual hardware which has a function of distributing interruptions from the hardware or the processing time of a CPU. Also, the operating system (OS) monitoring system has a function of permitting data to be read and written between the plurality of operating systems. The operating system monitoring system monitors the operations of the operating systems by periodically checking the writing of the data and the written data and carries out re-loading of the operating systems when detecting the trouble.
Also, Japanese Laid Open Patent Application (JP-P2001-101034A) discloses a trouble recovering system for control between different operating systems. The trouble recovering system of this conventional example uses a computer system in which a plurality of operating systems run simultaneously. The trouble recovering system has first to fourth units. The first unit assigns hardware resources to the plurality of operating systems. The first unit also attains, by using a software technique, a firewall as a virtual wall for isolating software and hardware such that a trouble of the hardware or the operating system has no influence on the execution of the other operating systems. Also, the first unit transmits information between the respective operating systems. The second unit monitors the operation states of the operating systems and an application program from an isolated operation environment and detects a trouble, stop and an operation impossible state of either of the operating systems. The third unit normally or forcedly stops the troubled operating system (OS). The fourth unit re-starts the operating systems. Thus, the trouble recovering system recovers the system automatically at the time of the trouble occurrence by combining them.
Also, Japanese Laid Open Patent Application (JP-A-Heisei 11-85547) discloses a virtual cluster configuring method. The virtual cluster configuring method of this conventional example has a virtual cluster configuring unit and an inter-virtual-cluster communicating unit. The virtual cluster configuring unit has dedicated hardware resources such as a processor, a physical memory, and an external device, and configures a plurality of virtual clusters, on which an operating system run on a single computer. In the inter-virtual-cluster communicating unit, processes on the different virtual clusters communicate with each other.